General Questions
Application Tips
Common Paint Problems and SolutionsGENERAL
QUESTIONS
What do primers-sealers do?
Primers-sealers provide a variety of performance properties such as stain blocking,
corrosion inhibition, surface filling, and enhanced hide. Their main function is to
satisfy the porosity of the surface so the topcoat does not penetrate into the substrate.
The result is a surface, when topcoated, that looks better and lasts longer.
What is an enamel?
An oil or water-based, stain resistant, washable topcoat which is characterized by its
ability to form a smooth, hard surface. Typically associated with a high gloss, but may
also include lower degrees of gloss.
How should mildew be removed?
Remove all mildew from the surface by scrubbing with a chlorine bleach solution (one part
bleach and three parts water) or a commercial mildew remover, while wearing rubber gloves
and eye protection. Rinse thoroughly and paint as soon as the surface is dry to avoid
recontamination.
What needs to be done if I'm repainting over a gloss paint?
Lightly sand to dull the sheen and clean the surface thoroughly. When recoating with an
oil-based paint or Porter's ADVANTAGE 900 Interior/Exterior Acrylic Enamel, you may paint
directly over glossy surfaces as long as they are clean.
Is a natural bristle brush better than a synthetic bristle brush?
The answer depends on the type of paint you plan to use. Natural bristle and synthetic
brushes may be used with oil-based paints. Only synthetic bristle brushes should be used
with latex or acrylic paints. (The water in latex or acrylic paints takes the oils out of
natural bristles and they become unmanageable).
How do you determine what type of roller cover to use?
Use a quality cover for an easier, more uniform application. Lambswool is recommended for
some oils and epoxies, otherwise use a quality synthetic fiber roller cover. A 3/8"
to 1/2" nap roller cover is recommended for wall paint being applied to smooth
drywall or plaster. Rough plaster and stucco walls may require a 3/4" to 1" nap
cover. Use a 1 1/4" nap cover when painting concrete block or other extremely rough
surfaces and the 3/16" nap cover is recommended to apply an ultra smooth finish when
using an enamel.
Can a latex paint be applied over an alkyd enamel?
Traditionally, latex finishes cannot be applied to an alkyd enamel without proper surface
preparation which includes sanding, cleaning, and priming. However Porter's ADVANTAGE 900
Interior/Exterior Acrylic Enamel, with its new age acrylic resin, may be applied directly
to clean alkyd enamel surfaces.
Is there a paint that can be used to prevent moisture from seeping through basement
walls?
A product containing Portland cement such as Porter's BLOC-LOC Waterproofing Block Filler
can be used to waterproof masonry surfaces. Extreme moisture leakage, however, may require
more extensive measures such as applying a vapor barrier material to the exterior surface
of the walls, or contacting a certified waterproofing contractor to evaluate and repair
the problem.
How can I paint my baseboard without getting paint on the carpet?
There are tools designed especially for this purpose. The Super Guide by Hyde® Tools is a
metal shield that can be placed between the carpet and the baseboard allowing you to paint
one section at a time. Another method is taping the carpet with masking tape or masking
paper.
My windows have been painted shut. How do I open them?
Trim along the sealed area with a knife and gently apply pressure to separate.
What is the best exterior trim paint: acrylic or alkyd?
100% acrylic topcoats are typically the best due to color retention properties and
flexibility. It is important, however, to use an oil based primer before using the acrylic
topcoat when painting over bleeding woods like Redwood or Cedar. A complete acrylic system
may be used on all other non-bleeding woods.
What causes exterior paint to chalk?
Some degree of chalking is normal. Some paint manufacturers have even touted this as a
"self-cleaning" process. However, excessive film erosion can result in unsightly
heavy chalk. Excessive chalking is caused by the disintegration of the paint film during
weathering. Some common causes of heavy chalking include application to an unsealed
surface, overspreading the paint, or poor quality paint. All can lead to premature
breakdown by the weather.
Can paints be applied in cool weather?
Most latex or acrylic paints should not be applied when temperatures are below 50° F.
Porter's ACRI-SHIELD LTC Low Temperature Exterior Acrylic paints may be applied as low as
35° F. Alkyd/oil based paints may be applied in temperatures as low as 40° F.
Why is it not recommended to paint in direct sunlight?
Paint needs to be liquid for a period of time for proper penetration and adhesion after
application. The heat from the sun can cause the outer layer of the paint film to dry
prematurely which could result in solvent entrapment, which can cause blisters to form.
What is the most common cause of blistering and peeling paint on exterior wood?
The most common cause is moisture. But blistering can also be caused by painting in direct
sunlight, inadequate surface preparation, or using a low quality exterior paint.
Can aluminum or vinyl siding be painted?
Vinyl siding or new aluminum may be painted with a 100% acrylic finish without priming, as
long as the surface is clean and dry. Weathered aluminum needs to be cleaned and then
primed with an oil based primer before applying the acrylic topcoat. When painting vinyl
siding, be sure that the color chosen is a shade no darker than the original color because
dark colors absorb heat from the sun and may cause warping or buckling.
What steps are involved in painting my metal lawn furniture?
Wire brush to remove any loose or chipping paint, sand any rusted areas, spot prime those
areas with a rust inhibitive primer like Porter's GLYPTEX Rust Inhibitive Primer No. 296
and finish with an oil based topcoat like Porter's GLYPTEX Urethane Gloss Enamel No. 4139
Series. Do not use a latex because it may become tacky when hot.
My gutters have peeled. How do I paint them?
The most common cause for gutter peeling is improper surface preparation. Power wash or
wire brush the gutters to remove any loose material. Spot prime bare areas with PORTER
GUARD Galvanized Metal Primer No. 290 for galvanized gutters, PORTER GUARD Alkyd Metal
Primer No. 276 for copper or PORTER GUARD DTM Acrylic Primer/Finish No. 215 for painted
aluminum gutters. Topcoat with a 100% acrylic like Porter's ACRI-SHIELD Acrylic Finishes.
What type of coating is best for wood decks and fences?
Most decks are constructed of pressure treated lumber. A penetrating deck stain tends to
work best on the horizontal surfaces (flooring) of decks due to constant foot traffic. The
vertical surfaces of decks and fences may be stained or painted according to personal
preference. Check the porosity of the wood before attempting to stain by sprinkling water
on the surface. If the water beads, then the stain will not penetrate the wood. If the
deck is new, let it age for about 30 days and check the porosity again. If it is an
existing deck, a deck cleaner and powerwasher may be used to prepare the surface for
staining.
What is the best way to "rejuvenate" an old brush with dried paint in it?
Dried latex paint can be removed by soaking brushes in denatured alcohol and cleaning with
a brush comb. You could also use a commercial brush cleaner for synthetic brushes like
Sav-A-Brush® powder by Red Devil. Simply mix with water and soak brushes to remove dried
paint. Oil based paint can be removed by soaking brushes in a liquid brush & roller
cleaner which is especially formulated for oil based paints.
What do I do with old leftover paint?
A small amount of latex paint may be allowed to dry out naturally (adding cat litter will
speed the process) and deposited in the trash. For oil-based paints, check with your local
county environmental agency for a hazardous waste disposal facility near you.
What size brush should I use?
Let the surface you are painting be your guide. The larger the surface, the larger the
tool you will need. For exterior siding, use a 4" brush. Use a 3" brush for
exterior gutters. For painting interior trim, use a 1" to 2 1/2" brush. The most
important guide, however, is to select a brush that is comfortable to use.
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